Circuit board holders and assemblies

ABSTRACT

A circuit board holder has or is provided with a face plate and with walls projecting from an inside of that face plate. A pair of opposite ones of such walls are equipped with circuit board retainers. Such retainers may be inside and/or outside of a space in the circuit board holder. The circuit board holder is equipped with one or more holder retainers or resilient snaps for releasably retaining that circuit board holder in an aperture of a panel. Such holder retainers or resilient snaps may have serrations for engaging panels of different thicknesses at their apertures. Such panel may be provided with a slot or slots at that aperture for access to the holder retainer or resilient snaps through the panel. The holder retainer or resilient snap may be released through such slots, such as by screwdrivers or other release tool, for removal of the circuit board holder or similar device from the panel.

FIELD OF THE INVENTION

[0001] The subject invention relates to circuit board holders andcircuit board assemblies.

BACKGROUND

[0002] The utility of printed and other circuit boards is well known.

[0003] In the field of circuit breakers, the art has evolved progressivemethods and circuit breaker housings for conveniently mounting circuitbreakers in corresponding apertures of power switching panels, such asapparent from U.S. Pat. No. 4,812,793, by Bohdan Krasij, issued Mar. 14,1989 for “Circuit Breaker Housing With Centered Actuator.” Circuitbreaker housings such as shown in FIG. 9 of that patent have been andare being sold as “dummies” for covering up panel apertures where nocircuit breaker is being mounted at the time. Commercial versions ofsuch dummies accommodate different mounting panel thicknesses byserrations at ends of so-called wings 220c shown in that patent.

[0004] In the circuit board field, there exists a need for improvedcircuit board holders and assemblies. By way of example and not by wayof limitation, the need is particularly pressing in applicationsrequiring rapid circuit board replacements, preferably without powerinterruption. One example in this respect is the alarm circuit field,such as in telephone exchange and the like, where circuit boards ofalarm systems need to be replaced without disruption of power todistribution circuits.

SUMMARY OF THE INVENTION

[0005] It is an object of the invention to provide improved methods ofmaking circuit board holders.

[0006] It is a germane object of the invention to provide improvedcircuit board holders.

[0007] It is a related object of the invention to provide improvedmethods of making circuit board assemblies.

[0008] It is a related object of the invention to provide improvedcircuit board assemblies.

[0009] Other objects will become apparent in the further course of thisdisclosure.

[0010] From a first aspect thereof, the invention resides in a method ofmaking a circuit board holder and, more specifically, resides in theimprovement comprising, in combination, providing that circuit boardholder with a face plate and with walls projecting from an inside ofthat face plate, equipping a pair of opposite ones of such walls withcircuit board retainers and equipping that circuit board holder with aholder retainer for releasably retaining that circuit board holder inthe mentioned aperture of the panel.

[0011] From a related aspect thereof, the invention resides in a circuitboard holder comprising, in combination, a face plate and wallsprojecting from an inside of that face plate, circuit board retainers ata pair of opposite ones of such walls, and a holder retainer at an edgeof the face plate.

[0012] The circuit board retainers may be inside and/or outside of thecircuit board holder.

[0013] From another aspect thereof, the invention resides in a method ofmounting a device, such as a circuit board holder, in an aperture of apanel, comprising, in combination, providing that device with aresilient snap for releasably retaining that device in the panel at thataperture, providing the panel with a slot at that aperture for access tothe resilient snap through that panel, and releasing such resilient snapthrough that slot for removal of the device from the panel.

[0014] From a related aspect thereof, the invention resides in acombination of a panel having an aperture, a device, such as a circuitboard holder, retained in that aperture by a resilient snap at an edgeof that aperture, and a slot in such panel at that aperture exposing theresilient snap through the panel at an edge of the mentioned aperture inthat panel.

[0015] Embodiments of the invention extend to assemblies of such circuitboard holders with circuit boards therein and with circuit panels.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The subject invention and its various aspects and objects willbecome more readily apparent from the following detailed description ofpreferred embodiments thereof, illustrated by way of example in theaccompanying drawings which also constitute a written description of theinvention, wherein like reference numerals designate like or equivalentparts, and in which:

[0017]FIG. 1 is a perspective view of a circuit board holder accordingto an embodiment of the invention;

[0018]FIG. 2 is a longitudinal section through the circuit board holderaccording to FIG. 1, with an inserted circuit board according to afurther embodiment of the invention, and with such circuit boardassembly releasably retained in a corresponding aperture of a panel;

[0019]FIG. 3 is an exploded view of a circuit board assembly showinginsertion of a circuit board into a circuit board holder according to arelated embodiment of the invention;

[0020]FIG. 4 is a top view of that circuit board assembly;

[0021]FIG. 5 is a top view of a fraction of a panel for mounting acircuit board holder or similar device according to an embodiment of theinvention; and

[0022]FIG. 6 is a view similar to FIG. 5 with a section through aninserted circuit board holder or similar device and through a releasetool pursuant to an embodiment of the invention.

MODES OF CARRYING OUT THE INVENTION

[0023] The drawings illustrate methods of making circuit board holders,improved circuit board holders and assemblies of such circuit boardholders with circuit boards therein, pursuant to the subject inventionand embodiments thereof.

[0024] Methods of making a circuit board holder 10, according toembodiments of the invention for installation in an aperture 12 of apower panel 13, provide that circuit board holder with a face plate 14larger than that aperture and with walls 16, 17, 18 and 19 projectingfrom an inside 20 of that face plate. Those embodiments of the inventionequip a pair 16 and 18 of opposite ones of the walls 16, 17, 18 and 19with circuit board retainers 21 and 22 and/or 33 and 34. Thoseembodiments of the invention further equip the circuit board holder 10with a holder retainer 23 for releasably retaining that circuit boardholder in the mentioned aperture 12 of the panel 13.

[0025] Plastics material molding or other well-known manufacturingtechniques may be employed for making the circuit board holders hereindisclosed.

[0026] In apparatus terms, a circuit board holder 10 according to anembodiment of the invention installable in the aperture 12 of panel 13according to the illustrated embodiments of the invention comprises aface plate 14 larger than that aperture 12 and walls 16, 17, 18 and 19projecting from the inside 20 of that face plate, circuit boardretainers 21 and 22 and/or 33 and 34 at a pair of opposite ones of suchwalls, such as walls 16 and 18, and a holder retainer 23 at an edge 25of the face plate. Such holder retainer may be spaced from that faceplate by a distance corresponding to a thickness 26 of the panel, suchas seen in FIG. 2 showing an assembly of the circuit board holder 10with a panel 13 and a circuit board 28.

[0027] At least one of another pair of the walls 16 to 19 may beprovided with or has a lateral opening covering at least one half ofthat wall. FIG. 1 by way of example shows both pairs of walls 17 and 18with such lateral openings 30 and 31 providing, for instance, access toone or more installed circuit boards 28, such as for cooling air and thelike, or for other purposes. In that case, the space 20 is still insidethe circuit board holder.

[0028] Within the scope of the invention, various devices and featuresmay be used as circuit board retainers. By way of example and not by wayof limitation, circuit board retainers may be provided internally of thespace 20 inside the circuit board holder 10, such as seen at 21 and 22,and may therefor be termed “internal circuit board retainers.”Alternatively or preferably additionally, circuit board retainers may beprovided externally of the inside space 20, such as seen at 33 and 34,and may therefor be termed “external circuit board retainers.”

[0029] Accordingly to the embodiments of the invention shown in FIGS. 2to 4, a circuit board 28 or 280 is inserted into the circuit boardholder 10. The inserted circuit board 28 or 280 is substantiallyretained in a first direction inside of the circuit board holder, suchas with internal circuit board retainers 21 and 22, and is substantiallyretained in a second direction, such as transversely to that firstdirection, externally of the inside space 20 of the circuit boardholder, such as with external circuit board retainers 33 and 34.

[0030] The circuit board retainers 21 and 22, according to theillustrated embodiment of the invention, include or are shaped as spacedrails for slideably receiving a circuit board 28 or 280. In thisrespect, FIGS. 1 and 3 show several such circuit board retainers orspaced rails 21 and 22 in each of the pair of opposite walls 16 and 18,respectively, for slideably receiving at least one circuit board 28 atone of several levels in the circuit board holder. Alternatively, two ormore circuit boards may be accommodated in one circuit board holder 10.

[0031] According to the illustrated embodiment of the invention, thecircuit board holder 10 has or is provided with external circuit boardretainers 33 and 34 in addition to the internal circuit board retainers21 and 22.

[0032] Also according to the illustrated embodiment of the invention,the pair of opposite walls 16 and 18 has or is provided with extensions36 and 37 beyond the inside 20 of the circuit board holder 10. Suchextensions 36 and 37 are equipped with circuit board retainers, or suchcircuit board retainers 33 and 34 are on these extensions 36 and 37,respectively.

[0033] By way of example, as illustrated in FIGS. 2 and 4, the circuitboard 28 is releasably retained with circuit board retainers inside ofthe circuit board holder 10 and is stabilized in that circuit boardholder.

[0034] Notwithstanding such terminology, the external circuit boardretainer 33 and 34 may serve as circuit board stabilizers and may servethe purpose of retaining circuit boards 28 and 280 in the circuit boardholder, or the retainers 21 and 22 and 33 and 34 may jointly retain andstabilize the circuit board in the circuit board holder.

[0035] As seen in FIGS. 1 and 2, the circuit board holder 10 accordingto an embodiment of the invention has or is equipped with accommodations38 and 39 at rails 21 and 22, respectively. Such accommodations 38 and39 may be a narrowing of the holder structure permitting the holderretainers 23 and 24 to be bent inwardly for a release of the circuitboard holder 10 from the panel 13.

[0036] Alternatively or additionally, the accommodations 38 and 39 mayin effect be circuit board stops at a distance 40 from a rear of theface plate 14.

[0037] Within the scope of the invention, the circuit board 28 may beprovided with a frontal portion 51 of reduced width relative to asubsequent main portion 52 of that circuit board. Such circuit board maybe inserted in the circuit board holder 10 by inserting the frontalportion 51 of reduced width in between the spaced external circuit boardretainers 33 and 34 and by thereupon forcing apart such spaced circuitboard retainers with the main portion 52 of the circuit board and bycontinuing insertion of the circuit board into the circuit board holderso that the circuit board is releasably retained with the internalcircuit board retainers 21 and 22 inside of the circuit board holder andis stabilized in that circuit board holder with the external circuitboard retainers and stabilizers 33 and 34.

[0038] By way of example, the external circuit board retainers andstabilizers 33 and 34 may be forced apart by flexure of the wallextensions 36 and 37.

[0039] In this or any other manner within the scope of the invention,the circuit board holder includes an inserted circuit board 28 or 280extending across that circuit board holder between the pair of oppositewalls 16 and 18 and circuit board retainers 21 and 22. Such insertedcircuit board preferably also extends between the circuit boardretainers or stabilizers 33 and 34, such as shown in FIGS. 2 and 4.

[0040] According to the embodiment of the invention shown in FIGS. 3 and4, one or more circuit board stops 380, such as at the kind of distance40 shown in FIG. 1 from a rear of the face plate 14, may be provided inthe circuit board holder for stopping insertion of a circuit board 280at a leading edge or corner 55. Alternatively or additionally, catches133 and 134 corresponding to the external circuit board retainers 33 and34, respectively, may be provided in the circuit board, such as seen inFIG. 3, in order to retain an inserted circuit board in a predeterminedposition, such as shown in FIG. 4.

[0041] In apparatus terms, an inserted circuit board 280 has lateralcatches 133 and 134 externally of a space 20 inside a circuit boardholder which has extensions 36 and 37 of a pair of opposite walls 16 and18, and circuit board retainers 33 and 34 are on those extensions andlateral catches.

[0042] According to the embodiment shown in FIGS. 3 and 4, these catches133 and 134 are lateral notches in the circuit board 280 into which theexternal circuit board retainers 33 and 34 come to rest when the circuitboard is completely inserted into its holder. However, within the scopeof the invention, different forms of retainers and catches than thoseillustrated in the drawings may be employed at 33/133 and 34/134. Forinstance, instead of being concave as shown in FIGS. 3 and 4, thecatches 133 and 134 may, for instance, be convex, and the externalretainers 33 and 34 may be correspondingly concave so as to receive suchconvex catches.

[0043] Within the scope of the invention, the wall extensions 36 and 37and external circuit board retainers 33 and 34 may be subdivided intoexternal circuit board retaining fingers that may alternate with theinternal circuit board retainer rails or shelves 21 and 22.

[0044] The above mentioned holder retainer 23 preferably is or is shapedas a resilient snap for releasably retaining the circuit board holder 10in the aperture 12 of the panel 13. As seen in the drawings, such holderretainer may include or be shaped as a pair of resilient snaps 23 and 24at the pair of opposite walls 16 and 18 for releasably retaining thecircuit board holder in aperture 12 of panel 13.

[0045] By way of example and not by way of limitation, such snaps 23 and24 may be the so-called wings 220c shown in the above mentioned U.S.Pat. No. 4,812,793 for circuit breaker housings.

[0046] As seen in FIGS. 1 to 3, there may be one or more apertures 42 inthe face plate 14, and a signal lamp 43 may be in any or each of thoseapertures and may be connected to the circuit board 28, for instance.Such apertures 42 may be of a knock-out type, being covered in the faceplate 14 until needed.

[0047] By way of example and not by way of limitation, the circuit board28 is shown with components 45, circuitry 48, and terminals 49, andsimilar components may, of course, be provided in the circuit board 280.

[0048]FIGS. 2, 5 and 6 show provision of the panel 13 with an aperture12 for receiving the circuit board holder 10. According to an embodimentof the invention illustrated in FIGS. 5 and 6, the panel 13 is providedwith a slot 56 at the aperture 12 for access to the holder retainer orresilient snap 23 through that panel 13. That embodiment of theinvention also effects release of the holder retainer 10 through theslot 56 for removal of the circuit board holder from the panel.

[0049] In this respect, FIG. 5 shows the circuit board holder 10 only bya dotted outline of its face plate 14 so as to avoid obstruction of theaperture 12 with lateral slot extensions or slots 56 and 57. Conversely,FIG. 6 shows the circuit board holder 10 in section through its walls 16to 19 behind its face plate. In FIG. 6, most of the holder retainers orresilient snaps 23 and 24 are covered up by the panel 13 and aretherefore shown by dotted lines, except where they cross under the slots56 and 57.

[0050] In apparatus terms, the panel 13 has an aperture 12 adapted toreceive the walls 16 to 19 of the circuit board holder 10 behind theface plate 14 seen in FIGS. 1 to 5. A slot 56 in that panel at thataperture exposes the holder retainer or snap 23 through the panel at anedge of that aperture 12 in the panel.

[0051] In FIGS. 5 and 6, the components 14, 16 to 19, 23 and 24 ifpresent may signify a device other than a circuit board holder.Accordingly, FIGS. 5 and 6 may be seen as illustrating a method ofmounting a device, such as a circuit board holder, in an aperture 12 ofa panel 13, comprising, in combination, providing that device with aresilient snap 23 for releasably retaining that device in the panel atthat aperture, providing the panel with a slot 56 at that aperture foraccess to the resilient snap 23 through that panel, and releasing suchresilient snap through that slot for removal of the device from thepanel 13.

[0052] In this respect, FIGS. 5 and 6 also illustrate a combination of apanel 13 having an aperture 12 and a device, such as a circuit boardholder 10, retained in that aperture by a resilient snap 23 at an edgeof that aperture, and a slot 56 in such panel at that aperture exposingsuch resilient snap through the panel at an edge of the mentionedaperture in that panel 13.

[0053] As seen in FIG. 6, the embodiment of the invention currentlyunder consideration also provides a tool 58 insertable through slot 56.By way of example and not by way of limitation, the tool 58 may be ascrewdriver or similar device which has a blade or similar implementhaving lateral dimensions smaller than the slot 56 so as to beinsertable therein and therethrough to the holder retainer or resilientsnap 23. In this or any other manner within the scope of the invention,the holder retainer or resilient snap 23 may be released with a tool 56insertable through slot 56. Such release, may, for instance, be effectedby depression of the resilient snap 23 toward the device 10 or its wall16, until the depressed snap 23 clears the aperture 12 for a removal ofthe circuit board holder 10 or other device from the panel 13.

[0054] According to an embodiment of the invention, the holder retainer23 is provided with steps or serrations 230 for mounting the circuitboard holder 10 in different mounting panels, including the mountingpanel 13 of thickness 26 such as shown in FIG. 2 and mounting panels ofother thicknesses, such as seen also in FIG. 6.

[0055] In principle, and within the scope of the invention, there needonly be one holder retainer or resilient snap 23, in which case only onelateral slot 56 and only one release tool 58 is required. However, wherethere are a pair of resilient snaps 23 and 24 at the pair of oppositewalls 16 and 18, such as shown in FIGS. 1 to 4, for releasably retaininga circuit board holder 10 or similar device in the aperture 12 of apanel 13, such as shown in FIGS. 2, 5 and 6, then there need to be apair of corresponding slots 56 and 57 and a pair of corresponding tools58 and 59 for a simultaneous release or depression of both resilientsnaps 23 and 24, such as seen in FIG. 6 for the desired removal of thedevice 10 from the panel 13. There also may be panel-accommodatingserrations 230 and 240 in each holder retainer or resilient snap 23 and24, respectively.

[0056] Accordingly, pursuant to conventional patent practice,expressions such as “a slot” and “a tool” employed in this descriptionand in accompanying claims implicitly stand for “at least one slot” and“at least one tool,” respectively, extending to a provision orutilization of two slots, such as shown at 56 and 57 and two releasetools, such as shown at 58 and 59 in FIG. 6, for instance.

[0057] This extensive disclosure will render apparent or suggest tothose skilled in the art various modifications and variations within thespirit and scope of the invention.

I/We claim:
 1. In a method of making a circuit board holder, theimprovement comprising in combination: providing said circuit boardholder with a face plate and with walls projecting from an inside ofsaid face plate; equipping a pair of opposite ones of said walls withcircuit board retainers; and equipping said circuit board holder with aholder retainer for releasably retaining said circuit board holder insaid aperture of the panel.
 2. A method as in claim 1, wherein: at leastone of another pair of said walls is provided with a lateral openingcovering more than one half of that one wall.
 3. A method as in claim 1,wherein: said circuit board retainers are provided inside of saidcircuit board holder.
 4. A method as in claim 1, wherein: said circuitboard retainers are provided externally of an inside space of saidcircuit board holder.
 5. A method as in claim 1, wherein: said circuitboard retainers are provided inside of said circuit board holder andexternally of an inside space of said circuit board holder.
 6. A methodas in claim 1, wherein: a circuit board is inserted into said circuitboard holder and is substantially retained in a first direction insideof said circuit board holder and is substantially retained in a seconddirection externally of an inside space of said circuit board holder. Amethod as in claim 1, wherein: said pair of opposite walls is providedwith extensions beyond said inside of the circuit board holder; and saidextensions are equipped with external circuit board retainers.
 8. Amethod as in claim 1, wherein: said circuit board retainers are shapedas spaced rails for slideably receiving a circuit board.
 9. A method asin claim 1, wherein: said circuit board retainers are shaped as severalspaced rails in each of said pair of opposite walls for slideablyreceiving at least one circuit board at one of several levels in saidcircuit board holder.
 10. A method as in claim 1, wherein: said holderretainer is shaped as a resilient snap for releasably retaining saidcircuit board holder in a panel.
 11. A method as in claim 1, wherein:said holder retainer is shaped as a pair of resilient snaps at said pairof opposite walls for releasably retaining said circuit board holder ina panel.
 12. A method as in claim 1, wherein: a circuit board isinserted in said circuit board holder and is releasably retained withsaid circuit board retainers inside of said circuit board holder.
 13. Amethod as in claim 1, wherein: said circuit board holder is providedwith external circuit board retainers in addition to internal circuitboard retainers; and a circuit board is inserted in said circuit boardholder and is releasably retained with said internal circuit boardretainers inside of said circuit board holder and is releasably retainedin said circuit board holder with said external circuit board retainers.14. A method as in claim 1, wherein: said circuit board holder isprovided with spaced external circuit board retainers in addition tointernal circuit board retainers; a circuit board is provided with afrontal portion of reduced width relative to a subsequent main portionof said circuit board; and said circuit board is inserted in saidcircuit board holder by inserting said frontal portion of reduced widthin between said spaced external circuit board retainers and by thereuponforcing apart said spaced external circuit board retainers with saidmain portion of said circuit board and continuing insertion of saidcircuit board into said circuit board holder so that said circuit boardis releasably retained with said internal circuit board retainers insideof said circuit board holder and is stabilized in said circuit boardholder with said external circuit board retainers.
 15. A method as inclaim 1, wherein: said circuit board retainers are shaped as spacedrails for slideably receiving a circuit board; and said circuit boardholder is equipped with circuit board accommodations at said rails at adistance from a rear of said face plate.
 16. A method as in claim 1,wherein: said circuit board retainers are shaped as spaced rails forslideably receiving a circuit board; and said circuit board holder isequipped with circuit board stops at said rails at a distance from arear of said face plate.
 17. A method as in claim 1, wherein: saidcircuit board holder is provided with spaced external circuit boardretainers in addition to internal circuit board retainers; a circuitboard is provided with catches corresponding to said external circuitboard retainers; and said circuit board is inserted in said circuitboard holder and is retained in said circuit board holder with saidexternal circuit board retainers and corresponding catches.
 18. A methodas in claim 1, wherein: said holder retainer is provided with serrationsfor mounting said circuit board holder in different mounting panels. 19.A method as in claim 1, including: providing a panel with an aperturefor receiving said circuit board holder; providing said panel with aslot at said aperture for access to said holder retainer through saidpanel; and effecting release of said holder retainer through said slotfor removal of said circuit board holder from said panel.
 20. A methodas in claim 1, including: shaping said holder retainer as a resilientsnap for releasably retaining said circuit board holder in a panel;providing a panel with an aperture for receiving said circuit boardholder; providing said panel with a slot at said aperture for access tosaid resilient snap through said panel; and effecting release of saidresilient snap through said slot for removal of said circuit boardholder from said panel.
 21. A method as in claim 20, including:providing a tool insertable through said slot; and releasing saidresilient snap with said tool through said slot in said panel.
 22. Amethod of mounting a device in an aperture of a panel, comprising incombination: providing said device with a resilient snap for releasablyretaining said device in said panel at said aperture; providing saidpanel with a slot at said aperture for access to said resilient snapthrough said panel; and releasing said resilient snap through said slotfor removal of said device from said panel.
 23. A method as in claim 22,including: providing a tool insertable through said slot; and releasingsaid resilient snap with said tool through said slot in said panel. 24.A method as in claim 22, wherein: said holder retainer is provided withserrations for mounting said resilient snap in different mountingpanels.
 25. A circuit board holder, comprising in combination: a faceplate and walls projecting from an inside of said face plate; circuitboard retainers at a pair of opposite ones of said walls; and a holderretainer at an edge of said face plate.
 26. A circuit board holder as inclaim 25, wherein: at least one of another pair of said walls has alateral opening covering more than one half of that one wall.
 27. Acircuit board holder as in claim 25, wherein: said circuit boardretainers are inside of said circuit board holder.
 28. A circuit boardholder as in claim 25, wherein: said circuit board retainers areexternal of an inside space of said circuit board holder.
 29. A circuitboard holder as in claim 25, wherein: said circuit board retainers areinside of said circuit board holder and are external of an inside spaceof said circuit board holder.
 30. A circuit board holder as in claim 25,wherein: said pair of opposite walls has extensions beyond an inside ofthe circuit board holder; and circuit board retainers are on saidextensions.
 31. A circuit board holder as in claim 25, wherein: saidcircuit board retainers include spaced rails on said pair of oppositewalls inside of said circuit board holder.
 32. A circuit board holder asin claim 25, wherein: said circuit board retainers include severalspaced rails in each of said pair of opposite walls.
 33. A circuit boardholder as in claim 25, wherein: said holder retainer is a resilientsnap.
 34. A circuit board holder as in claim 25, wherein: said holderretainer includes a pair of resilient snaps at said pair of oppositewalls.
 35. A circuit board holder as in claim 25, including: an insertedcircuit board extending across said circuit board holder between saidpair of opposite walls and circuit board retainers.
 36. A circuit boardholder as in claim 25, including: extensions of said pair of oppositewalls beyond an inside of the circuit board holder; circuit boardretainers on said extensions; and an inserted circuit board extendingacross said circuit board holder between said pair of opposite walls andextending between said circuit board retainers on said extensions.
 37. Acircuit board holder as in claim 25, wherein: said circuit boardretainers include spaced rails on said pair of opposite walls inside ofsaid circuit board holder; and said circuit board holder has circuitboard accommodations at said rails at a distance from a rear of saidface plate.
 38. A circuit board holder as in claim 25, wherein: saidcircuit board retainers include spaced rails on said pair of oppositewalls inside of said circuit board holder; and said circuit board holderhas circuit board stops at said rails at a distance from a rear of saidface plate.
 39. A circuit board holder as in claim 25, including: aninserted circuit board having lateral catches externally of a spaceinside said circuit board holder; extensions of said pair of oppositewalls; and circuit board retainers on said extensions and lateralcatches.
 40. A circuit board holder as in claim 25, including: anaperture in said face plate; and a signal lamp in said aperture.
 41. Acircuit board holder as in claim 25, including: panel-accommodatingserrations in said holder retainer.
 42. A circuit board holder as inclaim 25, in combination with: a panel having an aperture adapted toreceive said walls of said circuit board holder behind said face plate;and a slot in said panel at said aperture exposing said holder retainerthrough said panel at an edge of said aperture in said panel.
 43. Acombination as in claim 42, including: a holder retainer release toolhaving lateral dimensions smaller than said slot.
 44. In combination: apanel having an aperture; a device retained in said aperture by aresilient snap at an edge of said aperture; and a slot in said panel atsaid aperture exposing said resilient snap through said panel at an edgeof said aperture in said panel.
 45. A combination as in claim 44,including: a snap release tool having lateral dimensions smaller thansaid slot.
 46. A combination as in claim 44, including:panel-accommodating serrations in said resilient snap.